Reef-building corals only live in a limited temperature range.Like porridge, they should be 'not too hot and not too cold'.Coral reefs are concentrated in a band around the equator, between 30°N and 30°S latitude.Algae in corals need lightCorals grow in warm, clear, shallow waters that receive plenty of light.Most corals grow in the warmest water they can stand (about 85° F or 29° C). This means that slight increases in ocean temperature can harm corals.